SPECTRUM

Chemical Fact Sheet

Chemical Abstract Number (CAS #) 62737
CASRN 62-73-7
SynonymsDichlorvos
Phosphoric acid, 2,2-dichlorovinyl dimethyl ester
DDVP
Vapona
Analytical Method EPA Method 8141
Molecular FormulaC4H7Cl2O4P

Link to the National Library of Medicine's Hazardous Substances
Database for more details on this compound.

Use CHLORINATED ORGANIC PHOSPHATE INSECTICIDE WITH APPRECIABLE VAPOR PRESSURE. INCORPORATED INTO PLASTIC STRIPS IT SLOWLY RELEASES VAPOR. HAS BEEN APPROVED FOR USE IN DISINFECTION OF AIRCRAFT. CONTACT & STOMACH INSECTICIDE WITH FUMIGANT & PENETRANT ACTION. USED AS HOUSEHOLD & PUBLIC HEALTH FUMIGANT FOR PROTECTION OF STORED PRODUCTS @ 0.5-1 G AI/100 CU M; FOR CROP PROTECTION AGAINST SUCKING & CHEWING INSECTS @ 300-1000 G/HA. ANTIHELMINTIC-EG, FOR SWINE, DOGS, & HORSES Controls household, public health, stored product insects. Controls mushrooms, flies, aphids, spider mites, caterpillers, thrips, white flies in glasshouse crops, outdoor fruit, vegetables.
Consumption Patterns ESSENTIALLY 100% AS A PESTICIDE
Apparent Color COLORLESS TO AMBER LIQUID
Odor Mild chemical odor ; Aromatic odor
Boiling Point 140 DEG C @ 20 MM HG
Molecular Weight 220.98
Density 1.415 @ 25 DEG C/4 DEG C
Sensitivity Data Dichlorvos is not known to be an eye irritant.
Environmental Impact Dichlorvos may be released to the environment during its production, disposal and use as an insecticide in households and on crops and livestock. Dichlorovos is one of the more volatile organophosphates. If released into water it will hydrolyze with a half-life of approximately 4 days although its half-life varies considerably between pH 4 and 9. It will degrade very slowly at pH 4 and quite rapidly at pH 9. Biodegradation may aid in its disappearance, particularly when acclimated colonies of microorganisms exist or under more acidic conditions when hydrolysis is slower. Bioconcentration in fish will not be significant. The Henry's Law constant indicates that volatilization of dichlorvos from environmental waters and moist soil should generally be slow. The volatilization half-lives from a model river and a model pond, the latter considers the effects of adsorption, have been estimated to be 57 and over 400 days, respectively. If released on land, dichlorvos will leach into the ground water where it will hydrolyze and also degrade through chemical and biological processes with reported half-lives ranging from 1.5-17 days. If released into the atmosphere, dichlorvos is expected to exist almost entirely in the vapor phase in ambient air. In air, vapor phase dichlorvos will react with photochemically generated hydroxyl radicals and ozone with estimated half-lives of 2 and 320 days, respectivley. Human exposure will be primarily from indoor air where dichlorvos is used as an insecticide and from food which has been prepared where it is used.
Environmental Fate TERRESTRIAL FATE: When spilled on soil, dichlorvos leached into the ground with 18-20% penetrating to 30 cm within 5 days of spraying in one experiment. It will degrade by both hydrolysis and biodegradation. Half-lives of 7 days were obtained in clay, sandy-clay, and loose sandy soil . A half-life of 1.5 days was obtained in field plots on chestnut soil and 17 days in an unidentified soil . It disappeared from soil as well as foliage when sprayed on a vineyard in the USSR . Dissipation rates on lawns were measured with and without postspray irrigation, and it was not detected 24 hrs after application (detection limit 0.003 ug/sq cm) . AQUATIC FATE: When released into water, dichlorvos will remain in the aqueous phase since it will not adsorb appreciably to sediment. It will degrade primarily by hydrolysis although biodegradation may be important where acclimated microorganisms may exist such as some polluted waters or where the water is more acidic and hydrolysis slower. One investigator reported 64% disappeared in 24 hr at pH 8.7 and only 8% at pH 6. Half-lives in lakes and rivers are reported to be approximately 4 days . The Henry's Law constant indicates that volatilization of dichlorvos from environmental waters should generally be slow . Based on the Henry's Law constant, the volatilization half-life from a model river has been estimated to be 57 days(2,SRC). The volatilization half-life from a model pond, which considers the effects of adsorption, has been estimated to be over 400 days(3,SRC). ATMOSPHERIC FATE: Based upon the vapor pressure, dichlorvos is expected to exist almost entirely in the vapor phase in ambient air . In the atmosphere, vapor phase reaction with photochemically produced hydroxyl radicals may be important fate processes. Vapor phase reactions with ozone may also occur. The rate constant for the vapor-phase reaction of dichlorvos with photochemically produced hydroxyl radicals has been estimated to be 9.24X10-11 cu cm/molecule-sec at 25 deg C, which corresponds to an atmospheric half-life of about 2 days at an atmospheric concentration of 5X10 5 hydroxyl radicals per cu cm . The rate constant for the vapor-phase reaction of dichlorvos with ozone has been estimated to be 3.58X10-11 cu cm/molecule-sec at 25 deg C which corresponds to an atmospheric half-live of about 320 days at an atmospheric concentration of 7X10 11 molecules per cu cm . Dichlorvos will not directly photolyze in the atmosphere. Octanol water partition coefficients and air water partition coefficients were obtained for 10 organochlorine pesticides (including dichlorvos) as basic data for predicting their fate in the environment. The octanol water partition coefficient is 1.45X10 1 for dichlorvos. These values approximately correlated with the solubilities of these pesticides in water. The air water partition coefficient is 5.0X10-3 for dichlorvos.
Drinking Water Impact Dichlorvos has been detected in a water reservoir and water supply-irrigation system in the USSR and in 4 polluted rivers . On September 9 to 11, 1988, dichlorvos was detected in marine waters of Beirtreach Bay, Ireland at concentrations up to 0.13 ug/L . EFFL: Dichlorvos was detected in wastewater from a dichlorvos production plant in Bulgaria 16 g/l .

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